DC motor control help

Thread Starter

wewe

Joined Apr 9, 2010
31
hello , i made a generator for PWM signals on pic 16f877 , i am willing to use this to control a 1500 W DC motor
anyway i should have used a pic 18f because it can generate a dead time but it's too late for that , i don't want to re-write any code
so i would like to know if there's any IC that takes a pwm as an input and the output would be 2 PWMs with a dead time between them
if now what should i do with the circuit , i need a dead time that is almost 1 micro seconds or maybe 0.5 us
 

russpatterson

Joined Feb 1, 2010
353
Hi there. I did a motor controller with a PIC12f683 (no dead time PWM) but am only controlling a 15 watt motor. I ran across that deadtime and half bridge PWM stuff in a PIC18 datasheet and I don't really understand how that helps the motor control. Can you explain how it works and why it's necessary? Sorry I can't help you out.
 

Thread Starter

wewe

Joined Apr 9, 2010
31
to control a motor you must have 2 complementary pwms to control a H bridge of transistors (let's say MOSFETS)
when one pwm is on its rising edge the other is on its falling edge and vice versa , at this time there's a risk of activating all mosfets at the same time , which will cause a short circuit , so you need to generate a pwm where on each rising and falling edge there's a short amount of time where the output of both PWMs must be 0 in order not to risk it , this is called "dead time"
now , really no one here ever tried to control a DC motor with a pic 18f ??
its dedicated for DC motors for god's sake LOL
 
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